The invention relates to a communication device for a motor vehicle having several control units, which are connected to a data bus for the exchange of data. In particular, the invention relates to a communication device for a driver assistance system in a motor vehicle.
In driver assistance systems of a motor vehicle sensors are used which provide information concerning the vehicle surroundings. Such driver assistance systems are, for example, a lane change assistant or a bottleneck assistant. The latter requires the monitoring of both sides of the vehicle. As a rule, pairs of sensors are used for this purpose, which each monitor one side of the vehicle by sensing. For a lane change assistant, the sensors are, for example, in each case, mounted laterally at the rear of the vehicle. In this case, their monitoring ranges will partially overlap.
The sensors are connected with respective sensor control units which process the sensor data acquired by the sensors. Typically, one of the two sensor control units, as the master, transmits the information, such as detected objects or areas, which can be traveled without collisions, (also called free spaces), present in both sensor control units, by way of a data bus to at least one additional control unit. The sensor control unit operating as the master communicates with the other sensor control unit, which operates as a slave, by way of an internal data bus in order to exchange, for example, raw sensor data or data concerning the inherent movement of the vehicle. By mutually linking the two sensor control units, the sensor pair can provide more exact information concerning recognized objects or free spaces than when the data acquired individually by a respective sensor are individually provided to the data bus.
Such a communication device is schematically illustrated in FIG. 1. The sensor control unit operating as the master is marked SSG1; the sensor control unit operating as a slave is marked SSG2. The sensor control units SSG1 and SSG2 are mutually connected by way of an internal data bus PB for the exchange of data. Each of the two sensor control units SSG1, SSG2 is connected with a respective sensor not shown in detail, which, in particular, have mutually overlapping sensor acquisition ranges and are arranged, for example, at the rear or the front of a vehicle. The sensor data acquired by the sensors are transmitted to each of the sensor control units SSG1, SSG2 for further processing. Furthermore, the sensor control units SSG1, SSG2 are also used for the controlling, for example, the configuration, of the respective sensors. Together, the sensor control units SSG1, SSG2 form a control unit arrangement SGA, which is connected by way of a data bus SB with a control unit BDC of the motor vehicle. Actually, the physical connection exists only between the control unit SSG1 operating as the master and the control unit BDC. The control unit BDC may, for example, be a central control unit of the motor vehicle.
By way of the data bus SB, data DFC are provided to the control unit arrangement SGA by the control unit BDC, which, within the scope of a functionality F1, concern a diagnosis of the control unit arrangement SGA and/or of the sensors connected to the latter, a coding or a programming (flashing). The corresponding functionality F1 is taken over by the sensor control unit SSG1 operating as the master (“master diagnosis”). The same applies to the implementation of a calibration, which represents a functionality F3. For this purpose, the sensor control unit SSG1 operating as the a master provides calibrating data KD to the sensor control unit SSG2 operating as a slave. It is to be ensured thereby that the overlapping range implemented by the two sensors is defined.
Within the scope of its function as master for the control unit arrangement SGA, the sensor control unit SSG1 receives unprocessed or preprocessed sensor data OS2→1 from the control unit SSG2 operating as the slave, in order to process these data by means of a functionality F2 with the own sensor data and transmit a result of the processing as application data AD2 of the control unit arrangement SGA by way of the data bus to the control unit BDC.
In order to permit a preprocessing of the sensor data, as a rule, also odometric data of the vehicle, i.e. data concerning the inherent movement of the vehicle relative to its surroundings, are required. The control unit arrangement SGA receives corresponding data FDD (“driving dynamics data) from the control unit BDC. These data are received by the sensor control unit SSG1 operating as the master and are transmitted by way of a gateway GWFDD to the sensor control unit SSG2. Odometric data (“driving dynamics data”) are therefore present in each of the sensor control units SSG1, SSG2, so that the corresponding sensor data can in each case be related to them. The data preprocessed to object data OS2→1 by the sensor control unit SSG2 can then be processed by the sensor control unit SSG1 to form overall information.
FIG. 1 further illustrates an additional control unit SAS which is coupled by way of an additional data bus DB with the control unit BDC for the exchange of data. The control unit SAS represents, for example, a special functionality which requires not only abstracted application data AD2 as made available by the control unit BDC but detailed application data concerning the situation acquired by the sensors. While the application data AD2 contain, for example, only the information that a vehicle is approaching from the left rear relative to the own vehicle, the control unit SAS for providing its functionally requires detailed information concerning the vehicle approaching from the rear, such as the distance to the own vehicle, the relative speed to the own vehicle, etc. Such information can easily be provided by the control unit arrangement. In the topology illustrated in FIG. 1, these expanded application data then have to be transmitted by way of the data bus SB, the control unit BDC, the data bus DB to the control unit SAS. Because of an at least temporarily large volume of the expanded application data, an excessively high data load may occur on the data bus, by which other functionalities could be impaired.
It is an object of the present invention to provide a communication device as well as a method for operating a communication device which avoids the occurrence of an excessive bus load.
This object is achieved by a communication device according to the invention as well as by a method according to the invention.
The invention provides a communication device for a motor vehicle. The communication device comprises a first control unit, a second control unit and a control unit arrangement. Furthermore, a first data bus is provided to which the first control unit and the control unit arrangement are connected for the exchange of data. The second control unit and the control unit arrangement are connected to a second data bus for the exchange of data. The control unit arrangement comprises at least a first sensor control unit for controlling a first sensor and a second sensor control unit for controlling a second sensor. The first and the second sensor have mutually overlapping sensor acquisition ranges. By way of a third data bus, the first and the second sensor control unit can exchange at least preprocessed sensor data. The first and the second sensor control unit are designed to be operated in a master-slave operation with respect to at least one functionality. In this case, by way of the first sensor control unit as a master of a first functionality, first data, which are provided at the first data bus by the first control unit, are processed for the control unit arrangement. By way of the second sensor control unit as the master of a second functionality, first application data for the second control unit are provided at the second data bus.
The invention further provides a method for operating a communication device for a motor vehicle. The communication device comprises a first control unit, a second control unit and a control unit arrangement which comprises at least a first sensor control unit for controlling a first sensor and a second sensor control unit for controlling a second sensor, the first and the second sensor having mutually overlapping sensor acquisition ranges. A first data bus is further provided to which the first control unit and the control unit arrangement are connected for the exchange of data. The second control unit and the control unit arrangement are connected to a second data bus for the exchange of data. In the case of the method according to the invention, the first and the second sensor control unit exchange at least preprocessed sensor data by way of a third data bus. The first and the second sensor control unit are operated in a master-slave operation with respect to at least one functionality, whereby, by way of the first sensor control unit as the master of a first functionality first data, which are provided by the first control unit at the first data bus, are processed for the control unit arrangement, and whereby, by way of the second sensor control unit as the master of second functionality first application data for the second control unit are provided at the second data bus.
As a result of the communication device according to the invention, the technical complexity of the communication device and higher costs because of specific components are avoided in that the sensor control units of the control unit arrangement are operated depending on the functionality in a different master-slave configuration. This particularly results in the advantage that the first data bus connecting the first control unit and the control unit arrangement does not have to carry an excessively high bus load. This is a result of the fact that the data-intensive first application data are provided by the second sensor control unit operated as a master, which sensor control unit is not connected to the first data bus. The communication device according to the invention can be obtained in that the different functionalities of the control unit arrangement do not occur simultaneously, whereby the flexible defining of master and slave can be controlled by way of the corresponding providing of the functionality in each of the sensor control units.
In an expedient further development, the first data of the first functionality include data concerning the maintenance and/or diagnosis of the control unit arrangement.
In contrast, the second functionality includes the preprocessing of measuring data acquired by the first and the second sensor, the preprocessed measuring data being provided as first application data, which include objects acquired by the sensors and the information concerning the position and/or movement relative to the first and second sensor. The first application data thereby include processed raw data of the sensors, in which case, these are generated by processing and/or combining the respective sensor data. The first application data include, for example, information concerning all objects detected by the sensors. Objects represent a collection of reflection points which can be combined to form a unit. Such a unit may then, for example, correspond to a vehicle, a motorcycle, a pedestrian, a bicyclist, etc. The combination of all detected objects of the two sensor control units is called a “fusion”, wherein the data of the fusion correspond to the first application data. On the basis of these detailed first application data, the second control unit may, for example, provide a functionality intended for a driver assistance system.
According to a further development, the second functionality includes the processing of measuring data acquired by the first and the second sensor, whereby a result of the processing is made available as second application data by way of the first sensor control unit as a slave to the first data bus for the processing by the first control unit. The second application data therefore include only abstracted information, which is determined from the sensor data. The second application data include, for example, only abstract information, such as “vehicle from the left rear”, “vehicle from the right rear”, etc. Such abstracted information can be transmitted with a small bandwidth from the control unit arrangement, particularly the first sensor control unit connected with the first data bus to the first control unit for further processing.
Accordingly, the first application data may have a greater data volume, particularly a volume several times larger, compared to the second application data. The second application data are reduced to an abstract level, for example, by a reduction of the fusion data or of the first application data. In this specification, such first application data are also called a “warning”.
In an advantageous further development, sensor data of the first sensor are provided to the second sensor control unit as the master of the second functionality by the first sensor control unit for processing. The master of the second functionality is capable of determining the first as well as the second application data from these sensor data. As explained above, the providing of the extensive first application data takes place by the sensor control unit, which operates as the master of the second functionality. The providing of the second application data which are comparatively fewer takes place by the sensor control unit operating as the slave in that the corresponding data are transmitted by way of the third data bus first within the control unit arrangement.
According to a further advantageous embodiment, data required for an odometry computation are provided to the second sensor control unit as the master of the second functionality by the first sensor control unit for processing, which data are provided by the first control unit at the first data bus. The transmission of the data required for the odometry computation within the control unit arrangement, in turn, takes place by way of the third data bus.
In a further advantageous embodiment, calibrating data are provided by the second sensor control unit as the master of a third functionality to the first sensor control unit as the slave. A calibration is required in order to adapt the acquisition range of the two sensors to one another in a defined manner. Also with respect to this functionality, one of the two units takes over the function of the master while the other has the function of the slave.
The first sensor control unit and the second sensor control unit each have two bus connections. In particular, the first sensor control unit and the second sensor control unit may be of an identical construction with respect to their hardware. This leads to savings of production costs because different sensor control units do not have to be provided. The same applies to the storage or control during working processes. Which of the sensor control units then becomes the master and which becomes the slave with respect to a functionality will be defined solely by the corresponding software of the concerned sensor control unit. As explained above, the different functionalities cannot occur simultaneously, so that the flexible defining of master and slave can be adjusted by way of the corresponding software of the sensor control units.
The first and the second sensor form a pair of sensors, whose sensors are, for example, optical sensors or radar sensors.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of one or more preferred embodiments when considered in conjunction with the accompanying drawings.